Suppression of honeycombing in cathode nickel



Aug. 17, 1954 w. cooK ETAL 2,586,757

\ SUPPRESSION oF HoNEYcoMBING 1N cATHoDE NICKEL Filed Jan. 15, 195s mafxmk ATTORNEY honeycombing Patented Aug. 17, 1954 SUPPRESSION OF HONEYCOMBING IN CATHODE NICKEL Wilfred James Cook, Wilbur Vernon Barker, and Joseph Howard Tuck, Port Colborne, Ontario, Canada, assignors to The International Nickel Company, Inc., New York, N. Y., a corporation of Delaware Application January 15, 1953, Serial No. 331,480

Claims priority, application Canada November 21, 1952- 16 Claims.

\ 1 The present invention relates to improved electroreiining of nickel and, more particularly, to

a process for proucing sound cathode nickel and to an electrolyte for use in said process.

For many years, 'the art of electrorening nickel was confronted with the problem of honeycombing ln some instances, the problem was more serious than in others. Many different factors, such as process variables, construction materials, electrolyte composition variables, etc., were scrutinized in a search for the cause of honeycombing but this scrutiny revealed neither the cause of nor a. solution to this problem. Efforts to solve the problem of honeycombing by making a large number of changes and. variations in the process, the apparatus, the electrolyte composition, the treatment of the mother blanks used in producing the starting sheets, etc., Were not fully acceptable as a wholly successful solution on a commercial scale to the problem of honeycombing rlhus, the addition of cobalt into the electrolyte, for example, as cobalt chloride, was not effective in suppressing Likewise, using other means, suchf as nickel peroxide for precipitating cobalt, Was not satisfactory. Changing the materials of whichthe apparatus was composed, for example,`

replacing the cotton on the cathode boxes with synthetic fibers, replacing the pine side sticks on the electrolytic cell with cypress or protecting the Yside sticks with various materials, did not solve the problem. The addition of various addition `agents to the correction tank, for example, cu-

prous chloride, sodium hypochlorite, sulfur dioxide, hydrogen peroxide and combinations thereof, also was unsuccessful. Adding to the cathode boxes or compartments various chemicals, such as sodium chlorate, sodium perborate,

potassium permanganate, manganous sulfate, co-

balt chloride, cupric sulfate, ferrous sulfate, boric ents usually overcome pitting which is a diiierent condition generally attributed by those skilled in the art to be due to the adherence of cathodically `evolved hydrogen. Other unacceptable expedients which were tried include (1) varying the process conditions, for example, decreasing the current density, operating the process at various reduced pI-Ivalues, boiling thepuried electrolyte under vacuum or varying-.the rate of flow of the electrolyte; (2) modifying the process, for example, by triple pressing through an oxidizing slime While adding oxidizing agents, such as chlorine, hydrogen peroxide or sodium hypochlorite, ahead of the filter` press; and (3) pretreating the stainless steel mother blanks upon which the cathode nickel starting sheets are electro-` deposited with various agents, for example, nitric acid, hydrofiuoric acid, etc. Although these and many other attempts were made to overcome the foregoing. difficulties and to solve the problem of honeycombing, none was entirely successful when carried into practice commercially on an industrial scale.

It has now been discovered that improved, sound, pure nickel` cathodes substantially free from honeycombing can be produced in an electrorefining operation in an improved and eiiicient manner, utilizing the sulfate-chloride electrolyte process, by the addition of critical amounts of special organic compounds to the purified electrolyte.

It is an object of the present invention to provide an improved. process for producing sound nickel cathodes substantially free from honeycombing.

Another object of the invention is to provide an improved bath from which nickel cathodes, substantially free from honeycombing, may be deposited by electrolysis.

Still another object of the invention is to provide a method for suppressing or eliminating honeycombing in electrorened cathode nickel.

It is a further object of the invention to provide an improved nickel electrorening process for the production of sound nickel cathodes substantially free from honeycombing While utilizing the sulfate-chloride electrolyte.

Other objects and advantages will become apparent from the following description taken in conjunction with the accompanying drawings, in which:

Figure 1 is a reproduction of a photomacrograph at 1 Idiameter of a cross section of a honeycombed nickel cathode; and

Figure 2 is a reproduction of a photoinacrograph at 1 diameter of a cross section of a sound nickel cathode produced in accordance with the present invention.

Generally speaking, the present invention contemplates a process for the production of coinmercially acceptable cathode nickel substantially freefrom the deleterious effects of honeycombing which comprises electrolyzing an aqueous electrolyte having a pI-I between about 3.0 and about 5.0 and containing about 40 to about 70 s. p. 1. (grams per liter) of nickel, about 12 to about 30 g. p. l. of sodium, about 18 to about 55 g. p. l. of chloride radical, about 65 to about 115 g. p. l. of sulfate radical, about 15 to about 25 g. p. l. of boric acid and about 0.0003 to about 0.001 g. p. l. of at least one terminally substituted polyethylene oxide condensate selected from the group consisting of a polyethylene oxide condensate of m-methyl p-octyl phenol containing 8 to 11 moles of ethylene oxide per mole and a polyethylene oxide condensate of lauryl alcohol containing 4 to 6 moles of ethylene oxide per mole to electrodeposit sound nickel at the cathode. The electrolysis is carried out while maintaining the electrolyte temperature between about 100 F. and about 160 F. and While employing a current density up to between about and about 25 amperes per square foot. The catholytemay contain a total of up to about 0.004 g. p. l. of such impurities as copper, iron, arsenic, lead, etc., without affecting the operating characteristics of the process. In addition, the catholyte may be saturated with respect to calcium ions. Thus, it may contain up to about 0.6 g. p. l. of calcium., without affecting the operating characteristics of said process. The process utilizing the aforementioned electrolyte is applicable not only to the production of commercial cathode nickel but also to the production on mother blanks of the thin nickel cathode starting sheets employed in producing commercial cathode nickel.

The aforementioned terminally substituted polyethylene oxide condensates, a polyethylene oxide condensate of m-methyl p-octyl phenol containing 8 to 11 moles of ethylene oxide per mole and a polyethylene oxide condensate of lauryl alcohol containing 4 to 6 moles of ethylene oxide per mole, which are utilized as honeycombsuppressing agents in carrying out the present and where n is 4 to 6 If more than 0.001 g. p. l., for example 0.005 g. p. l., of said compounds is present in the catholyte, the production of the cathode nickel is detrimentally affected due to the fact that the resultant cathodes becomes highly stressed and/ or Warped. Stresses set up in the nickel deposited on the stainless steel mother blanks t'oform the cathode starting sheets and due to excessive amounts of the aforementioned compounds are often so great that the cathode nickel separates from the mother blanks and the resulting starting sheets are badly warped. Attempts to straighten these warped starting sheets are defeated by their springy rea-ction due to the high stresses. The production of the commercial cathode nickel is also adversely affected when excessive amounts of the additives are employed in that the cathodes become highly stressed and warped and diiculty is encountered in extricating these warped cathodes from the cathode boxes and in thereafter straightening them. When less than about 0.0003 g. p. l., for example, 0.0001 g. p. 1., of said The addition of the special compounds in the aforementioned critical amounts contemplated by the present invention has not been found to have any demonstrable effect upon the characteristics and properties of the electrolyte, other than that of substantially suppressing honeycombing. For example, no substantial decrease is found in the surface tension of the electrolyte. Thus, the surface tension of the electrolyte, as measured with a Cenco Du Nouy tensiorneter, prior to the introduction of the honeycombsuppressing agent contemplated by the present invention is usually about 76 to about 78 dynes .per centimeter when measured at 25 C.; and the surface tension of the electrolyte after introduction of the aforementioned honeycomb-suppressing agents in amounts contemplated by this invention is usually about 70 to about 78 dynes per centimeter when measured at 25 C., which compares with 72 dynes per centimeter as the surface tension of water determines under similar conditions. However, if excessive amounts of one of these compounds are added, such as about 0.01 g. p. l., the surface tension is radically lowered to about 35 to 40 dynes per centimeter which is indicative of a marked change in the characteristics and properties of the electrolyte and may have some relation to the fact that cathode nickel produced from such an electrolyte is unsatisfactory.

In carrying the invention into practice to produce cathode nickel, it is preferred to electrolyze an aqueous catholyte having a pH about 3.8 to 4.6 and containing about 40 to about 60 g. p. l. of nickel, about 18 to about 30 g. p. l. of sodium, about 65 to about 99 g. p. l. of sulfate radical, about 27 to about 51 g. p. l. of chloride radical, about 15 to about 25 g. p. l. of boric acid, about 0.0004 to about 0.0008 g. p. l. of the aforementioned honey-comb-suppressing agent, and the balance essentially water to electrodeposit nickel at the cathode. The electrolysis is carried out by passing electric current through an anode (in practice, usually impure nickel), the electrolyte and the cathode (usually a nickel starting sheet) while maintaining the temperature between about 130 F. and about 150 F. and while employing a current density between about l2 and about 20 amperes per square foot. Although an impure nickel anode containing about to about 96% of nickel is employed, the process is also operative when utilizing insoluble anodes. ,When using soluble impure nickel anodes, the composition of the anode is dependent upon the source of nickel. Thus, for example, in one industrial operation, the impure nickel anodes contain about 94% to about 96% of nickel, about 2.5% to about 3.5% of copper, about 0.7% to about 0.9% of cobalt, about 0.5% to about 1.0% of iron, about 0.002% to about 0.004% of lead, about 0.05% to about 0.07% of arsenic and about 0.5% to about 0.8%

offsulfur. It is further preferred that the electrolyte be continuously circulated from the cells through a purication system and back to the cathodes to prevent depletion of the constituents.

The electrolyte may advantageously be prepared by the anodic dissolution of nickel in a solution of` boric acid, sodium chloride and an i amount of sulfuric acid equivalent to the desired nickel. However, the dissolutionof nickel sulfate together with sodium chloride, boric acid and sodium carbonate for pH adjustment would be a preferred methodof preparing electrolyte. Prior to the production of cathode nickel in accordance with the present invention, the electrolyte may be subjected to various treatments and operations known to. the. art to: accomplish purposes, such as purification, conditioning, control, etc. For ex- .present invention may be carried out in any type of suitable electrolytic apparatus, including that referred to and/or disclosed in the Renzoni U. S. Patents Nos. 2,394,874 and 2,480,771. Thus, in actual practice, an impure nickel anode may be anodically corroded by a sulfate-chloride acid anolyte in the anode compartment of a compartmented electrolytic cell. This impure anolyte is then puried in a separate purication circuit with the removal of copper, iron, arsenic, and lead. The now-purified electrolyte is nally introduced into the cathode compartment of the aforementioned cell and electrolyzed to electrodeposit nickel on the cathode starting sheet.

For the purpose of giving those skilled in the art abetter understanding of the invention and a. better appreciation of the advantages of the invention, the following illustrative examples are given:

Eample I To a portion of an electrolyte which, after treatment with chlorine to remove cobalt, Was found to result in the production of honeycombed cathode nickel, about 0.0005 g. p. l. of polyethylene oxide condensate of m-methyl p-octyl phenol containing 8 to 11 moles of ethylene oxide per mole Was added. The electrolyte was not other- Wise modied in composition. The electrolyte, after the addition of the aforementioned amounts of honeycomb-suppressing agent, had a pH of 4.0 and contained 52 g. p. l. of nickel, 22 g. p. l. of sodium, 40 g. p. 1. of vchloride radical, 78 g. p. l. of` sulfate radical, 15 g. p. l. of boric acid, 0.0005 g, p. l. of a polyethylene oxide condensate of mmethyl, p-octyl phenol containing 8 to 11 moles of ethylene oxide per mole and the balance essentially water. The surface tension of this electrolyte, as measured by a Cenco Du Nouy Tensiometer at 25 C.,`was about 75 dynes per centimeter.

The aforementioned electrolyte containing the honeycomb-suppressing agent was electrolyzed to electrodeposit cathode nickel at the same current density and` temperature, i. e., 15 amperes per square foot and 140 as had initially produced honeycombed nickel. The resulting cathode nickel.

6j nickel produced therefrom` was found to be substantially stress free and unWarped and devoid of honeycombing. Upon macrographic examination the cathode nickel thus produced was found to have a sound structure similar to that shown in `Figure 2.

Example II To another portion of the same` electrolyte which, after treatment with chlorine to remove cobalt,` Wasfound to result in the production of honeycombed cathode nickel, about 0.0008 g. p. l. of a polyethylene oxide condensate of lauryl alcohol containing 4 moles of ethylene oxide per mole was added. 'I'he electrolyte was not otherwise modified in composition. The electrolyte, after the addition of the aforementioned amounts of honeycomb-suppressing agent, had a pH of 4.0 and contained 50 g. p. l. of nickel, 20 g. p. l. of sodium, 40 g. p. l. of chloride radical, 70 g. p. l. of sulfate radical, 6 g. p. l. of boric acid, 0.0008 g. p. l. of a polyethylene oxide` condensate of lauryl alcohol containing 4 moles of ethylene oxide per mole and the balance essentially water. The surface tension cf this electrolyte, as measured by a Cenco Du Nouy tensiometer, was about 72 dynes per centimeter. The aforementioned electrolyte containing the honeycomb-suppression agent was electrolyzed to electro-deposit cathode nickel at the same current density and temperature, i. e., l5 amperes per square foot and 140 F., as had initially produced honeycombed The resulting cathode nickel produced therefrom was found to be substantially stress free and unwarped and devoid of honeycombing. Upon macrographic examination the cathode nickel thus produced was found to have a sound structure similar to that shown in Figure 2.

Example III To still another portion of the same electrolyte which, after treatment with chlorine to remove cobalt, was found to result in the production of honeycombed cathode nickel, about 0.00045 g. p. l. of a polyethylene oxide condensate of lauryl alcohol containing 6 moles of ethylene oxide per mole was added. The electrolyte was not otherwise modified in composition. The electrolyte, after the addition of the aforementioned amounts of honeycomb-suppressing agent, had a pH of 4.0 and contained 56 g. p. l. of nickel, 26 g'. p. l. of sodium, 44 g. p. l. of chloride radical, 89 g. p. l. of sulfate radical, 17 g. p. l. of boric acid, 0.00045 g. p. l. of a polyethylene oxide condensate of lauryl alcohol containing 6 moles of ethylene oxide per mole and the balance essentially Water. The surface tension of this electrolyte, as measured at 25 C. by a Senco Du Nouy tensiometer, was about 75 dynes per centimeter. The aforementioned electrolyte containing the honeycombsuppressing agent Was electrolyzed to electrodeposit cathode nickel at the same current density and temperature, i. e., l5 amperes per square foot and F., as had initially produced honey-- ess utilizing applicants particular bath composition and operating conditions. Likewise, while particular emphasis has been placed upon the presence of the aforementioned honeycomb-suppressing agents in critical amounts in the electrolyte, it is not to be intended to imply that the remaining composition of electrolyte is unimportant. On the contrary, the presence of chloride radical in the electrolyte is an important aspect of the invention since honeycombing has not been observed to occur when the electrolyte is an allsulfate electrolyte devoid of chloride radical or is an electrolyte low in chloride radical. The invention is applicable in its broader aspects to the production of cathode nicke1 from any high chloride electrolyte having a composition within the ranges set fourth hereinbefore where it is desired to insure the suppression of honeycombing in cathode nickel.

Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and Variations may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. rlhus, for the purposes of this invention cobalt is the equivalent of nickel. Such modiiications and variations are considered to be within the purview and scope of the invention and appended claims.

We claim:

1. A process for the electrorening of nickel from an aqueous nickel-containing solution which comprises establishing a catholyte having a pH between about 3 and about 5 comprising between about Li to about 70 g. p. l. of nickel, about 12 to about 30 g. p. 1. of sodium, about 18 to about 55 g. p. l. of chloride radical, about 65 to about 115 g. p. 1. of sulfate radical, about 15 to about 25 g. p. l. of boric acid and about 0.0003 to about 0.001 g. p. l. of at least one compound selected from the group consisting of a compound having y the structural formula (llHs cmroHm-@o-(cmommmn where m is 3 to ll and a compound having the structural formula where n is 1 to 6 with the balance essentially water, and electrolyzing said catholyte while maintaining the temperature between about 100 F. and about 160 F. by passing electric current at a current density between about 5 and about 25 amperes per square foot through said electrolyte from an anode to a cathode to deposit sound .nickel cathodes.

Where m is 8 to 11 withthe balance essentially water, and electrolyz- 8. ing said catholyte while maintaining the temperature between about F. and about 160 F. by passing electric current at a current density between about 5 and about 25 amperes pervsquare foot through said electrolyte from an anode to a cathode to deposit sound nickel cathodes.

3. A process for the electrorening of nickel from an aqueous nickel-containing solution which comprises establishing a catholyte having a pH between about 3 and about 5 comprising between about 40 to about 70 g. p. l. of nickel, about 12 to about 30 g. p. l. of sodium, about 18 to about 55 g. p. l. of chloride radical, about 65 to about 115 g. p. l. of sulfate radical, about 15 to about 25 g. p. l. of boric acid and abo-ut 0.0003 to about 0.001 g. p. l. of a compound having the structural formula with the balance essentially water, and electrolyzing said catholyte while maintaining the temperature between about 100 F. and about 160 F. by passing electric current at a current density between about 5 and about 25 amperes per square foot through said electrolyte from an anode to a cathode to depo-sit sound nickel cathodes.

4. A process for the electrorening of nickel from an aqueous nickel-containing solution which comprises establishing a catholyte having a pI-I between about 3 and about 5 comprising between about 40 to about '70 g. p. l. of nickel, about 12 to about 30 g. p. l. of sodium, about 18 to about 55 g. p. 1. of chloride radical, about 65 to about g. p. l. of sulfate radical, about 15 to about 25 g. p. l. of boric acid and about 0.0003 to about 0.001 g. p. l. of a compound having the structural formula CH3(CH2) 11--0-(CH2CH20) 6H with the balance essentially water, and electrolyzing said catholyte while maintaining the temperature between about 100 F. and about 160 F. by passing electric-current at a current density between about 5 and about 25 amperes per square foot through said electrolyte from an anode to a cathode to deposit sound nickel cathodes.

5. A process for the electrorening of nickel from an aqueous nickel-containing solution which comprises establishing a catholyte having a pH between about 3.8 and about 1.6 comprising between about 40 to about 60 g. p. l. of nickel, about 18 to about 30 g. p. l. of sodium, about 27 to about 51 g. p. l. of chloride radical, about 65 to about 99 g. p. l. of sulfate radical, about 15 to about 25 g. p. 1. of boric acid and about 0.0004 to about 0.0008 g. p. 1. of at least one terminally substituted polyethylene oxide condensate selected from the group consisting of a polyethylene 0X- ide condensate of m-methyl p-octyl phenol containing 8 to 11 moles of ethylene oxide per mole and a polyethylene oxide condensate of lauryl alcohol containing 4 to 6 moles of ethylene oxide per mole with the balance essentially water, and electrolyzing said catholyte while maintaining the temperature between about E. and about F. by passing electric current at a current density between about l2 and about 25 amperes per square foot through said electrolyte from an anode to a cathode to deposit sound nickel cathodes.

6. A process for the electrorening of nickel from an aqueous nickel-containing solution which comprises establishing a catholyte having a pH between about 3.8 and about 4.6 comprising between about 40 to about 60 g. p. l. of nickel, about 25 g. p. 1. of boric acid and about 0.0004 to about 0.0008 g. p. 1. of a compound having the structural formula i onsroHQM-@eoaomommn where m is s to 11 with the balance essentially water, and electrolyzing said catho-lyte while maintaining the temperature between about 130 F. and about 150 F. by passing electric current at a current density between about 12 and about 25 amperes per square foot through said `electrolyte from `an anode to a cathode to deposit sound nickel cathodes.

'7. Aiprocess for the electroreiining of nickel from an aqueous nickel-containing solution which comprises establishing a catholyte having a pH between about 3.8 and about 4.6 comprising between about 40 to about 60 g. p. l. of nickel, about 18 to about 30 g. p. 1. of sodium, about 27 to about 51 g. p. l. of chloride radical, about 65 to about 99 g. p. l. of sulfate radical, about 15 to about 25 g. p. l. of bcric acid and about 0.0004c to about 0.0008 g. p. l. of a compound having the structural formula with the balance essentially water, and electrolyzing said catholyte while maintaining the temperature between about 130 F. and about 150 F. by passing electric current at a currentdensity between about 12 and about 25 amperes per square foot through said electrolyte from an anode to a` cathode to deposit sound nickel cathodes.

8. A process for the electrorening of nickel from an aqueous nickel-containing solution which comprises establishing a catholyte having a pH between about 3.8 and about 4.6 comprising between about 40 to about 60 g. p. 1. of nickel, about 18 to about 30 g. p. l. of sodium, about 27 to about 51 g. p. l. of chloride radical, about 65 to about 99 g. p. l. of sulfate radical, about 15 to about 25 g. p. l. of boric acid and about 0.0004 to about 0.0008 g. p. 1. of a compound having the structural formula with the balance essentially water, and electrolyzing said catholyte while maintaining the temperature between about 130 F. and about 150 F. by passing electric current at a current density between about 12 and about 25 amperes per square foot through said electrolyte from an anode to a cathode to deposit sound nickel cathodes.

9. A nickel electrorening electrolyte having a pH between about 3 and about 5 and containing about 40 to about 70 g. p. l. of nickel, about 12 to about 30 g. p. l. of sodium, about 18 to about 55 g. p. l. of chloride radical, about 65 to about 115 g. p. l. of sulfate radical, about 15 to about 25 g. p. 1. of boric acid and about 0.0003 to about 0.001 g. p. l. of at least one terminally substituted polyethylene oxide condensate selected from the group consisting of a polyethylene oxide condensate of m-methyl p-octyl phenol containing 8 to 11 moles of ethylene oxide per mole and a polyethylene oxide condensate of lauryl alcohol containing 4 to 6 moles of ethylene oxide per mole, the balance being essentially water.

10. A nickel electroreiining electrolyte having a pH between about 3 and about 5 and containing about-10 to about 70 g. .p. 1. of nickel, about 12 toabout 30 gip. l..of sodium, about 18 to about 55 g. p. l. of chloride radical, about 65 to about g. p. l. rof sulfate radical, .about 1.5 to about 25 g. p. l. of boric acid and about 0.0003 to about 0.001 g. p. l. of a compound having the structural formula where m is 8 to ll the balance being essentially water.

11. A nickel electrorening electrolyte having a pH between about 3 and about 5 and containing about 40 to about 70 g. p. l. of nickel, about 12 to about 30 g. p. l. of sodium, about 18 to about 55 g. p. l. of chloride radical, about 65 to about 115 g. p. l. of sulfate radical, about 15 to about 25 g. p. l. of boric acid and about 0.00013 to about 0.001 g. p. 1. of a compound having the structural formula the balance being essentially water.

12. A nickel electrorei'lning electrolyte having a pH between about 3 and about 5 and containing about i0 to about 'l0 g. p. l. of nickel, about 12 to about 30 g. p. l. of sodium, about 18 to about 55 g.A p. l. of chloride radical, about 65 to about 115 g. p. 1. of sulfate radical, about 15 to about 25 g. p. l. of boric acid and about 0.0003 to about 0.001 g. p. l. of a compound having the structural formula CH3 (CH2) 11-0- CHzCHzO) 6H the balance being essentially water.

13. A nickel electrorening electrolyte having a pH between about 8.8 and about 4.6 and containing about 40 to about 60 g. p. l. of nickel, about 18 to about 30 g. p. l. or" sodium,` about 27 to about 51 g. p. 1. of chloride radical, about 65 to about 99 g. D. 1. of sulfate radical, about 15 to about 25 g. p. l. of boric acid and about 0.0004 to about 0.0008 g. p. l. of at least one terminally substituted polyethylene oxide condensate selected from the group consisting of a polyethylene oxide condensate of m-methyl p-octyl phenol containing 8 to 11 moles of ethylene oxide per mole and a polyethylene oxide condensate of lauryl alcohol containing 4 to 6 moles of ethylene oxide per mole, the balance being essentially water.

14. A nickel electrorenning electrolyte having a pH between about 3.8 and about 4.6 and containing about 40 to about 60 g. p. 1. of nickel, about 18 to about 30 g. p. l. of sodium, about 27 to about 51 g. p. l. of chloride radical, about 65 to about 99 g. p. l. of sulfate radical, about 15 to about 25 g. p. l. of boric acid and about 0.0004 to about 0.0008 g. p. l. of a compound having the structural formula (IlHi cnaamw-@o-(ocumonn where m is 8 to 11 i 11 15 to about 25 g. p. l. of borc acid and about 0.0004 to about 0.0008 g. p. l. of a compound having the structural formula the balance being essentially Water.

16. A nickel electrorening electrolyte having a pH between about 3.8 and about 4.6 and containing about 40 to about 60 g. p. l. of nickel, about 18 to about 30 g. p. l. of sodium, about 27 to about 51 g. p. l. of chloride radical, about 65 to about 99 g. p. l. of sulfate radical, about 15 to about 25 g. p. l. of boric acid and about 0.0004 to about 0.0008 g. p. l'. of a compound having the structural formula CH3 (CH2) 11-O (CHzCHzO) 6H 5 the balance being essentially Water.

References Cited in the le of this patent UNITED STATES PATENTS 10 Number Name Date 1,970,578 Schoeller et al Aug. 21, 1934 2,294,311 Lind Aug. 25, 1942 2,480,771 Renzoni Aug. 30, 1949 

1. A PROCESS FOR THE ELECTROREFINING OF NICKEL FROM AN AQUEOUS NICKEL-CONTAINING SOLUTION WHICH COMPRISES ESTABLISHING A CATHOLYTE HAVING A PH BETWEEN ABOUT 3 AND ABOUT 5 COMPRISING BETWEEN ABOUT 40 TO ABOUT 70 G. P. L. OF NICKEL, ABOUT 12 TO ABOUT 30 G.P.L. OF SODIUM, ABOUT 18 TO ABOUT 55 G.P.L. OF CHLORIDE RADICAL ABOUT 65 TO ABOUT 115 G.P.L. OF SULFATE RADICAL, ABOUT 15 TO ABOUT 25 G.P.L. OF BORIC ACID AND ABOUT 0.0003 TO ABOUT 0.001 G.P.L. OF AT LEAST ONE COMPOUND SELECTED FROM THE GROUP CONSISTING OF A COMPOUND HAVING THE STRUCTURAL FORMULA 